Tufts OpenCourseware
Author: Amelia Virostko

1. Introduction

  1. Gram-negative bacteria with long, thing, helical or coiled shape
  2. Thin peptidoglycan cell wall, flagella, and outer membrane
  3. Only 3 genera cause disease in humans
    1. Treponema
    2. Borrelia
    3. Leptospira

2. Leptospirosis

  1. Encounter
    1. Prevalent in tropical and subtropical regions
    2. Contact with soil or water contaminated with urine from an infected animal
  2. Entry
    1. Pass through mucous membranes or skin abrasions
    2. Incubation from 7-13 days
  3. Spread/Multiplication
    1. Can spread to any organs, particularly kidneys
    2. May be found in CSF
  4. Damage
    1. High fever
    2. Headache
    3. Myalgia
    4. Conjunctival suffusion
    5. Hemorrhage
    6. Abdominal pain
    7. Vomiting
    8. Anicteric leptospirosis in 90%
      1. Less severe
      2. Lower fever, meningitis, uveitis, and rash
    9. Icteric leptospirosis
      1. Jaundice, hepatitis, renal failure, pulmonary and visceral hemorrhage, and carditis
      2. Rapidly fatal if untreated
  5. Virulence Factors
    1. Some strains produce hemolysin
    2. LPS
  6. Diagnosis
    1. Clinical
    2. PCR or ELISA
  7. Treatment
    1. Penicillin or doxycycline
    2. May require hemodialysis
  8. Outcome
    1. 40-70% fatality with icteric leptospirosis
    2. May cause residual headaches, uveitis, or psychologic disturbances

3. Lyme Disease (B. Burgdorferi)

  1. Encounter
    1. Transmitted through Ixodes ticks
    2. Often in late spring or early summer
    3. Most common on northeast coast and around the Great Lakes
  2. Spread/Multiplication
    1. Spread through skin over several days
    2. Spread to over organs over weeks
  3. Damage
    1. Early localized days after bite
      1. erythema migrans - non-itchy bulls-eye rash
    2. Early disseminated infection days to weeks after bite
      1. fever, malaise, arthralgia, neurologic manifestations, meningitis, and peripheral neuropathy
    3. Late Lyme disease months to years after bite
      1. arthritis with joint swelling in large joints
      2. polyradiculopathies or other PNS or CNS manifestations
      3. inflammatory skin lesion that leads to skin atrophy
  4. Virulence Factors
    1. Binds to complement factor H and to factor H-like protein to inhibit alternative complement pathway
    2. Alter Vls locus to evade immune system
    3. Few surface proteins therefore difficult for immune system to recognize it
  5. Diagnosis
    1. Often diagnosed clinically based on symptoms and patient history
    2. ELISA to detect IgM or IgG antibodies
  6. Treatment
    1. Oral doxycycline is drug of choice
    2. IV ceftriaxone if serious nervous system involvement
  7. Outcome
    1. Not fatal and usually clears with treatment
    2. Rarely develop antibiotic treatment-resistant chronic Lyme arthritis, which may be autoimmune-related

4. Syphilis (T. pallidum)

  1. Encounter
    1. Sexually transmitted or transplacental spread
  2. Spread/Multiplication
    1. Initially reside extracellularly, but spread by lympathic drainage
  3. Damage
    1. Primary syphilis 10-90 days after encounter
      1. chancre at site of inoculation
    2. Secondary syphilis 6 weeks to 6 months after primary infection
      1. 50% of affected individuals
      2. early systemic spread to lymph nodes, liver, joints, muscles, and distal skin
      3. disease abates in 1/3 of affected patients and no bacteria remain
    3. Tertiary syphilis years to decades after initial infection
      1. vasculitis, inflammation, gummas, and liver destruction
      2. tabes dorsalis, dementia, and motor function impairment
      3. aortic valve insufficiences and aortic aneurysms
  4. Virulence Factors
    1. Does not produce virulence factors or toxins
    2. Few surface proteins therefore difficult for immune system to recognize
  5. Diagnosis
    1. Serology tests for anti-cardiolipin antibiodies with RPR or VRDL tests
  6. Treatment
    1. Very sensitive to penicillins therefore treat with long-acting penicillins